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<h1 class="RH1">Atn Function</h1>
<p class="T">Returns the arctangent of a number.</p>
<p class="RL"><b>Syntax</b></p>
<p class="SYN"><b>atn</b>(<b>number</b>)</p>
<p class="DT1">Number&nbsp;&nbsp; is any valid
<a href="reference_numeric_expression.htm">numeric expression</a> that expresses 
the tangent of the angle you want.</p>
<p class="RL"><b>Remarks</b></p>
<p class="DT1">The <b>atn</b> function takes the ratio of two sides of a right 
triangle (number) and returns the corresponding angle in radians. The ratio is 
the length of the side opposite the angle divided by the length of the side 
adjacent to the angle.</p>
<p class="DT1">The range of the result is -<a href="reference_pi.htm">pi</a>/2 
to pi/2 radians.</p>
<p class="DT1">To express the arctangent in degrees, multiply the result by 
180/pi or use the <a href="reference_degrees.htm">degrees</a> function.</p>
<p class="RL"><b>Example</b></p>
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    <th>Expression</th>
    <th>Description (Result)</th>
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    <td>atn(1)</td>
    <td>Arctangent of 1 in radians, pi/4 (0.7854)</td>
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    <td>atn(1)*180/pi</td>
    <td>Arctangent of 1 in degrees (45)</td>
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    <td>degrees(atn(1))</td>
    <td>Arctangent of 1 in degrees (45)</td>
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